Few dive sites anywhere in the Mediterranean deliver a moment quite like it. You fin through a dark, cathedral-like tunnel carved through Gozo’s western cliffs, watching a pinprick of blue light grow larger and larger – until the rock suddenly gives way and you hang suspended above a wall that plunges into deep, indigo open water. This is the Inland Sea at Dwejra, and it is one of the most unforgettable dives in the Maltese Islands.

Jacques Cousteau is famously said to have ranked the Dwejra area among his favourite dives, and once you’ve passed through the tunnel it’s easy to understand why. Here’s everything you need to know about diving the Inland Sea with Watercolours Dive Centre.

Inland Sea Dive Site at a Glance

• Location – Dwejra, west coast of Gozo, behind the Chapel of St Anne

• Dive type – Shore dive with an easy, sheltered entry

• Depth – 2 m in the lagoon; the tunnel floor drops from around 3–6 m to roughly 26 m at the seaward exit; outer walls descend to 35–50 m+

• Level – Advanced Open Water recommended; the tunnel is an overhead-style environment with boat traffic on the surface

• Highlights – Cavern-like tunnel, dramatic light effects, sheer walls, abundant marine life, easy link to Azure Reef and the Blue Hole

• Conditions – Diveable in most conditions except strong west and north-west winds

What Is the Inland Sea?

The Inland Sea — known in Maltese as il-Qawra — is a shallow seawater lagoon roughly 60 metres across, enclosed by towering limestone cliffs on Gozo’s rugged west coast. Geologists believe it formed when the roof of a large sea cave collapsed along a fault line, leaving behind a sheltered pool connected to the Mediterranean by a single natural passage: an 80-metre tunnel running straight through the cliff face.

Above the surface, the lagoon is a picture-postcard scene of traditional fishermen’s boathouses and colourful luzzu boats ferrying sightseers through the arch. Below the surface, that same tunnel becomes the star of one of Gozo’s most iconic dives.

The Dive: Through the Tunnel and Into the Blue

Entry and the lagoon

Entry could hardly be easier. You kit up a few steps from the water and wade in over a pebble bottom that never exceeds a couple of metres in depth — ideal for final checks before the main event. There isn’t much to see in the lagoon itself, so most divers make a short surface swim to the tunnel mouth and begin the descent there.

The tunnel

The tunnel entrance starts shallow, at around 3–6 metres, then the floor falls away quickly — first to about 15 metres, then deeper still, reaching roughly 26 metres where the passage meets the open sea. The walls are near-vertical, dressed in sponges, corals and shade-loving invertebrates, and the pebble floor funnels you towards the light.

This is where the magic happens. As your eyes adjust to the darkness, the exit appears as a glowing blue keyhole in the distance. With every fin kick it widens, until you emerge from the rock into astonishingly clear open water — one of the great ‘wow’ moments in Mediterranean diving, and a dream backdrop for underwater photographers.

Outside the tunnel

Beyond the exit, the seabed shelves away to 35–50 metres and more, so this section rewards good buoyancy and depth awareness. Turn left or right and follow sheer reef walls riddled with cracks, fissures and small caverns. Recreational divers can enjoy a superb multi-level profile along the walls before returning through the tunnel; technical divers will find ledges and drop-offs continuing well beyond recreational limits.

For a longer adventure, the Inland Sea links naturally with its world-famous neighbours. Head south along the wall and you reach Azure Reef — the dramatic boulder field created when the Azure Window collapsed in 2017, now a maze of swim-throughs between 10 and 25 metres — with the option to exit via the Blue Hole. It’s one of the finest one-way dives in Gozo.

Marine Life at the Inland Sea

The nutrient-rich walls around the tunnel exit support a remarkable variety of Mediterranean marine life. Keep an eye out for:

• Amberjacks – hunting in pairs off the wall, alongside passing schools of barracuda

• Groupers, moray eels and octopus – tucked into cracks and holes in the reef

• Colourful nudibranchs – including the striking regal doris, plus sea hares and tube anemones for the macro enthusiasts

• John Dory, scorpionfish and cardinalfish – damselfish, wrasse and bream shoaling along the cliffs

On lucky days with excellent visibility, divers have even reported eagle rays gliding over the sand below the tunnel exit — a reminder to glance into the blue as well as at the wall.

Conditions, Safety and When to Dive

Thanks to its enclosed, cliff-protected setting, the Inland Sea is diveable in almost all conditions — only strong westerly or north-westerly winds rule it out. Visibility outside the tunnel is frequently outstanding, often exceeding 30 metres in the right conditions.

Two things deserve respect here. First, boat traffic: sightseeing boats run through the tunnel regularly, especially in summer, so divers should stay close to the tunnel walls, keep below the boats and take care when surfacing. Second, depth: the tunnel is effectively an overhead environment and the exit sits at around 26 metres, so solid buoyancy control and an Advanced Open Water certification (or equivalent) are strongly recommended. Nitrox is a great choice for extending bottom time along the outer walls.

Frequently Asked Questions

How deep is the Inland Sea dive site?

The lagoon itself is only about 2 metres deep. The tunnel floor drops from roughly 3–6 metres at the lagoon side to around 26 metres at the seaward exit, and the walls outside descend to 35–50 metres and beyond.

Do I need to be an advanced diver to dive the Inland Sea?

Advanced Open Water certification (or equivalent) is recommended. The tunnel involves reduced light and depth beyond 18 metres at the exit, and the outer walls drop off quickly. It’s also an ideal site for completing your Deep Diver specialty.

Is the Inland Sea a shore dive?

Yes. It’s one of the easiest entries in Gozo — a few steps down to a shallow pebble beach, with no long surface swims or rough entries.

Can you dive the Inland Sea, Azure Reef and Blue Hole together?

Yes. A popular route follows the wall south from the tunnel exit to Azure Reef and finishes at the Blue Hole, combining three of Gozo’s best dive sites in a single spectacular dive.

When is the best time to dive the Inland Sea?

The site is diveable year-round except in strong west or north-west winds. Early morning dives avoid the heaviest tour-boat traffic and offer the most dramatic light in the tunnel.

Dive the Inland Sea with Watercolours Dive Centre

The Inland Sea is more than a dive — it’s a rite of passage for anyone diving in Malta and Gozo. Whether it’s your first tunnel experience or a deep exploration of the outer walls and Azure Reef, our experienced guides know Dwejra’s conditions, routes and hidden corners inside out.

Ready to swim into the blue? Get in touch with Watercolours Dive Centre to book your Inland Sea dive, or explore our full range of guided dives and PADI courses across Malta, Gozo and Comino.